Install it normally. Then, create a directory on internal memory and copy all data files into it. For example, I created "/sdcard/mw/data-files/" (you better not have any spaces or any weird characters in the path):

Now copy contents of the steam version into it (I've only tested that one - and right now expansions are required or it will crash):

You could also set custom command line arguments (e.g. --skip-menu --start Balmora) and at the bottom you can select whether you want to use GLESv1 or GLESv2 renderer (one might work better than the other).

Once the game has started, there should be on-screen sticks (green circles inside red squares) - these emulate standard OpenMW gamepad so you use them to control mouse, camera and movement.

When the mouse cursor is visible, you can control it using your device screen as a virtual touchpad. To left click, tap the screen. To right click, tap the screen with two fingers. To open a virtual keyboard, tap the screen with three fingers.

The crossbow button is left click, sword&shield is right click (so menu), the up arrow is jump, arrow below it is space (action button), the rest you could probably figure out.

This port is using the gl4es library: https://github.com/ptitSeb/gl4es. gl4es translates GL1 calls into GLESv1/GLESv2 calls so they can run on mobile/portable devices. If you're a developer struggling to port a desktop OpenGL 1 application to mobile, check it out.

I got to lend a Galaxy Tab A (2016) running Android 7.0 for a quick test:
All the videos stuttered, but the game ran surprisingly well.
I only completed the character creation and explored the outskirts of Seyda Neen; including a small skirmish with two mudcrabs.
Indoors it ran quite well and even outdoors it wasn't too bad (I probably missed something but I wasn't able to display the current frame rate).